Polymer blends of polyethylene terephthalate and alpha-olefin,alpha,beta-unsaturated carboxylic acid copolymers



United States Patent US. Cl. 260857 Claims ABSTRACT OF THE DISCLOSURE Blend of polyethylene terephthalate and an ionic hydrocarbon copolymer of an alpha olefin and a 3-5 carbon 04,,3-BthYl6HlC3llY unsaturated acid, in which the carboxylic acid groups are randomly distributed over the copolymer. the acid groups may be neutralized. The blend may also contain polyhexamethylene adipamide.

This invention relates to polymers, and, more specifically, to blends of synthetic polymers.

Polyethylene terephthalate is produced on a large scale at relatively low cost, and finds extensive use in the production of synthetic fibers. It has not, however, been exploited as a molding resin due to its insufiicient tougrness for that utility. In contrast to polyethylene terephthalate, polyhexamethylene adipamide (66 nylon) has an excellent balance of properties for use as a molding resin.

This invention provides synthetic polymer blends which possess a combination of properties different from and superior to, in many respects, those of any of the individual components of the blends. For example, a surprising improvement in toughness is achieved in the blends of this invention. Moreover, this invention provides blended resins which exhibit less mold shrinkage and water uptake than does polyhexamethylene adipamide.

The synthetic polymer blends of this invention comprise polyethylene terephthalate and an ionic hydrocarbon copolymer of a-olefins and fi-ethylenically unsaturated carboxylic acids.

The ionic hydrocarbon copolymer employed as a component of the blends of this invention is a copolymer of a-olefins having the formula RCH=CH wherein R is a radical selected from the class consisting of hydrogen and alkyl radicals containing 1-3 carbon atoms, and a,,8- ethylenically unsaturated carboxylic acids containing 3-5 carbon atoms. The a-olefin content of the copolymer is at least 70 mole percent, based on the ionic copolymer,

The carboxylic acid groups are randomly distributed over the copolymer molecules and can be 0-10()% neutralized by metal cations distributed over the carboxylic acid groups of the copolymer. The metal cations can be derived from metals selected from the class consisting of Groups I, II, and IV of the Periodic Table of the elements published by the Fisher Scientific Company.

Illustrative of the u-olefins useful in the preparation of the ionic copolymer component of the blends of this invention are ethylene, propylene, butene-I and pentene-l.

Illustrative of a .,8-ethylenically unsaturated carboxylic acids useful in the preparation of said ionic copolymer are acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, maleic acid, fumaric acid, and monoesters of itaconic acid, maleic acid, and fumaric acid. Other monomers can, of course, be terpolymerized in the copolymer.

The carboxylic acid groups of the ionic copolymer component of the polymer blends are randomly distributed over the copolymer molecules. A technique by which this random distribution can be achieved is the following. The copolymerization of the a-olefin and the carboxylic acid monomers can be conducted in a one-phase system, that is, in a medium, such as benzene or ethylene, in which the monomers are soluble, The medium may be in either liquid or vaporized form. Preferably, and especially when relatively small amounts of the carboxylic acid component are desired in the copolymer, the process can be continuous, the monomers being fed into the reactor in the ratio of their relative polymer-forming reactivities, and the residence time in the reactor being limited to prevent all the alkylene monomer feed from being converted into polymer.

The relative proportions of polyethylene terephthalate and ethylene/methacrylic acid in the blends can be varied considerably. The weight of the ethylene/methacrylic acid copolymer present in the blend can be about 5-150% of that of polyethylene terephthalate. The preferred composition is that wherein the Weight of the ethylene/methacrylic acid copolymer is about 5-45% of that of polyethylene terephthalate. The optimum composition is that wherein the ethylene/methacrylic acid copolymer is about 25% of that of polyethylene terephthalate.

In a preferred embodiment of this invention, the polymer blends comprise polyethylene terephthalate and an ethylene/methacrylic acid copolymer comprising -97 weight percent ethylene and 3-20 weight percent methacrylic acid. The carboxylic acid groups of the ethylene/ methacrylic acid copolymer may be unneutralized or neutralized up to by a cation derived from a metal of Group I, II, or IV. Preferably, the carboxylic acid groups of the ethylene/methacrylic acid copolymer are neutralized to the extent of 40-60%. The preferred cations used in the neutralization of said carboxylic acid groups are Na K Ca++, Mg++, Zn++, and Ph Blends of polyethylene terephthalate and ionic hydrocarbon copolymer can be modified by the addition of polyhexamethylene adipamide (66 nylon). The weight ratio of the polyethylene terephthalate and ionic copolymer remain within the range described above, 'and the weight of polyhexamethylene adipamide can be about 20-500% of that of polyethylene terephthalate. The amount of polyhexamethylene adipamide added is chosen depending upon the particular properties desired in the product.

Terblends of polyethylene terephthalate, ethylene/ methacrylic acid copolymer, and polyhexamethylene adipamide are especially useful in the molding of precision parts.

The polymer blends of this invention can be further modified by the addition of pigments, fillers, etc. Illustrative of useful pigments are iron oxides, cadmium red, Rhodamine, chrome yellow, chrome green, and phthalocyanine blue. Fillers which can be added to the blends 3 4 of this invention are glass fiber, talc, chalk, asbestos, adipamide. These terblends show a marked decrease in polyethylene, and titanium dioxide. mold shrinkage as compared with that of polyhexamethyl- The synthetic polymer components of these blends can ene adipamide, accompanied by a striking dimunition of be prepared separately and then subsequently blended by water uptake. These data demonstrate the excellent ditechniques such as melt extrusion or batch mixing. mensional stability of the blends. Dimensional stability In order that the invention may be better understood 5 is important when the resin is to be employed in the fabrithe following detailed examples are given in addition to cation of precision parts. the examples already given above. The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limi- EXAMPLES rations are to be understood therefrom. The invention 1s not limited to the exact detalls shown and described since Blends were prepared by melt extrusion of a mixture obvious modifications will occur to those skilled in the art.

TABLE 1 Tensile Elongation, Flexural Izod Blend Compcsition Strength Percent Modulus, Impact,

p.s.i. p.s.i. it. lb./in.

notch Example Number:

I 80% PET; EIMAA; (10% MAA); (50% COO- as Zn++). 8,850 36 320, 000 1. 12 II 80% PET; 20% E/MAA; (10% MAA); (60% of (300- as Na 9,360 40 374, 000 0. 69 80% PET; 20% E/MAA; (10% MAA); (COO- unneut.) 9, 040 14 357,000 0. 52 PET 12, 900 5 465, 000 0. 26

1 PET is polyethylene terephthalate; E /MAA is ethylene/methacrylic acid copolymer; CO 0- refers to the carhoxylate groups of the acid copolymer.

Percentages are by weight except for percent neutralization of carboxylic acid groups.

TABLE 2 Tensile Flexural Izod Mold Water, Number: Blend 1 Composition Strength, Elongation, Modulus, Impact, Shrinkage, Uptake p.s.i. Percent p.s.i. it. lb./in. in. per in. Percent notch Example IV 70% PET; 25% PHMA; 5% E/MAA; (10% MAA); 8, 810 140 319, 000 0. 54 0. 003 2. 8

(50% OOO- as Zn++). V 47.5% PET; 47.5% PHMA; 5% E/MAA; (10% 9, 490 120 318, 000 0.95 0. 006 4. 5

MAA); (50% (300- as Zn++). B- 100% P MA 0. 015 9 1 PET, E/MAA, 000*, see footnote to Table 1. PHMA is polyhexamethylene adipamlde. Percentages are by weight except for percent neutralization of carboxylic acid groups.

of the respective components as described in Tables 1 I claim:

and 2. The extrnder employed was a National Rubber 1. Polymer blends comprising polyethylene tereph- Machinery Company 1 /2-inch extruder (length to dithalate and an ionic hydrocarbon copolymer, said ionic ameter ratio, 20) fitted with a torpedo-head mixing screw hydrocarbon copolymer being of a-olefins having the forand a /4-inch by A-inch die. Under typical extrusion mula RCH=CH wherein R is a radical selected from conditions the resin temperatures were 250 C. at the rear the class consisting of hydrogen and alkyl radicals conof the barrel, 280 C. at the front of the barrel, and 280 taining 1-3 carbon atoms, and u,[3-ethylenically unsat- C. at the die. The screw speed as 40 r.p.m. Blended maurated carboxylic acids containing 35 carbon atoms, the terial was extruded into a 15-20 C. aqueous quench bath. u-olefin content of the said ionic copolymer being at least Specimens of extruded blends were prepared for physical 70 mole percent based on the ionic copolymer, the cartesting y injection-molding 011 a 301111416 V8 1 D H boxylic acid content of said ionic copolymer being heciprocating-screw molding machine. The barrel temperatween 3 nd 20 Weight percent based on the ionic copolytllffi 0f the injection-mower Was alld the mold mer, the carboxylic acid groups of said ionic copolymer temperature 18 C. The extrusion cycle was 6/4 seconds. being randomly distributed over the copolymer molecules,

said carboxylic acid groups being 0*100% neutralized by Physical tests included those for ultimate tensile metal cations distributedover the carboxylic acid groups strength, percent elongation, flexural modulus, and Izod 55 impact Strength, as detefmilled y ASTM Procedures of the copolymer, said metal cations being derived from D638, D638, D790, and D256, respectively. Linear m ld metals selected from the class consisting of Groups I, shrinkage was measured. Water uptake was determined 11, and IV, the weight of the ionic hydrocarbon copolymer by boiling the specimen in water until the weight became present in the blend being about 5150% of that of polyconstant. ethylene terephthalate.

The P y test Speclmens of Examples L1H and 2. Polymer blends according to claim 1 wherein the Standard A i were anPealed at 9 for 16 ionic hydrocarbon copolymer is an ethylene/methacrylic hours under nitrogen so as to induce maximum crystalacid copolymer, the Weight of Sal-d copoiymer being ifig cfmPosltmPs E E g d 5-150% of that of polyethylene terephthalate, said ethyle p yslca test Speclmens 0 Xamp es an ene/methacrylic acid copolymer comprising 80-97 weight standard B (Table 2) were not annealed before tBStlIl. t th 1 d 3 20 h th H The data in Table 1 show that when an ionic hydro- 223 e y ene an welg t Percent me acry 6 carbon copolymer of the type herein described is blended into polyethylene terephthalate, the toughness of the resultant blend far exceeds that of the polyethylene tereph- Wmght of 531d ethylene/methacryhc acld copolymer 1S thalate alone. Due to this unexpected result the utility 5-45% of that of said Polyethylene terephthalateof polyethylene terephthalate in resin compositions is Polymar blends according to claim 2 Comprising enha ed, polyethylene terephthalate, an ethylene/methacrylic acid Table 2 describes terblends which are produced by the copolymer, and polyhexamethylene adipamide, the weight modification of the blends above by polyhexamethylene of said ethylene/methacrylic acid copolymer in the blend 3. Polymer blends according to claim 2 wherein the 6 being 5-150% of that of polyethylene terephthalate, and FOREIGN PATENTS the weight of polyhexamethylene adipamide bein 20- 5 8 1 6 500% of that of polyethylene terephthalate. a jg g gjg gfi 5. Polymer blends of claim 2 wherein 4060% of sald carboxyhc and groups are neutralized by said metal 5 SAMUEL HBLECH, Primary Examiner.

cations.

PAUL LIEBERMAN, Assistant Examiner. References Clted UNITED STATES PATENTS US. Cl. X.R. 3,207,816 9/1965 Dugliss 260-873 10 260-78, 873, 40, 41, 88.1 

